Electrostatic copier

ABSTRACT

A dry developer system for applying toner particles to copy material in which a sheet of copy material carrying a latent electrostatic image is conveyed face down past a serrated roller provided with magnetic means for holding particles of magnetic material carrying toner so oriented as to brush the surface of the copy material in a direction opposite to the direction of the advance of the material. The developer system further comprises a clapper for holding the copy material into contact with the particles on the roller.

Unite States atent [151 3,639,05 1

(Iharlap et al. 1 Feb. 1, 1972 [54] ELECTROSTATIC COPIER 3,003,46210/1961 Streich, Sr. ..l18/637 [72] lnventors: E. Paul Charlap,Scarsdale, N.Y.; Fritz 3088386 5/1963 Sugarman 3,145,122 8/1964 Stre1ch,Sr. mmmga'fem Gesmjfleuchelhem 3,164,074 1/1965 Francis et 31.. Flsche"G'essen Wlesck, 0f 3,176,652 4/1965 Mott et al ..118/637 ux Germany [73]Assignee: Savin Business Machines Corporation, FOREIGN PATENTS ORAPPuCATlONS New York, NY. 1,865,366 10/1963 Germany ..117/17.5

[22] Filed: 1969 Primary Examiner-Samuel S. Matthews [21] AppL No.1823,225 Assistant Examiner-Robert P. Greiner Attorney-Shenier & OConnorRelated US. Application Data [62] Division of Ser. No. 379,232, June 30,1964, Pat. No. [57] ABSTRACT 3,490,841 A dry developer system forapplying toner particles to copy material in which a sheet of copymaterial carrying a latent [52] U.S.Cl ..355/3,117/ 17.5 electrosiaticimage is conveyed face down P 3 Serrated [51] int. Cl. ..G03g 15/08roller Provided with magnetic means for holding Particles of [58 FieldofSearch.. ..117/17.5;355/3; 118/637 magnetic material carrying toner soOriented as to brush the surface of the copy material in a directionopposite to the 56] References Cited direction of the advance of thematerial. The developer system further comprises a clapper for holdingthe copy material into UNITED STATES PATENTS contact with the particleson the roller.

2,786,440 3/1957 Giaimo, Jr ..118/637 UX 4 Claims, 7 Drawing FiguresPATENTEUFEB H972 $639,051 sum 3 or 3 f /04 a o O l O INVENTORS .524 5,PAUL, cHARl-fl FRITZ gnu/v! cAm'feN L OTHAR FISCHER BYMXM ATTORNEYSELECTROSTATIC COPIER This application is a division of our c-opendingapplication Ser. No. 379,232 filed June 30, 1964, now US. Pat. No.3,490,843.

BACKGROUND OF THE INVENTION heretofore been proposed for using drydevelopers. Systems wherein developer is sprinkled and the like do notensure uniform distribution of toner over the face of the sheet to bedeveloped.

We have invented a dry developer system for electrostatic copiers whichovercomes the defects of developer systems of the prior art. Our systemenables us to avoid the use of liquids in our copying machine. Itensures uniform distribution of particles over the face of the sheetbeing developed.

SUMMARY OF THE INVENTION One object of our invention is to provide a drydeveloper system for electrostatic copying machines.

Another object of our invention is to provide a developer system whichdoes not require the use of liquid developers.

A further object of our invention is to provide a dry developer systemwhich ensures even distribution of toner across the face of the sheetbeing developed.

Other and further objects of our invention will appear from thefollowing description.

In general our invention contemplates the provision of a dry developersystem for developing a latent electrostatic image onthe face of acopying sheet in which a clapper moves the sheet into contact withmagnetic particles with toner carrying magnetic particles magneticallyheld in serrations in the surface of a roller which is driven in adirection counter to the movement of the copy sheet.

BRIEF DESCRIPTION OF THE DRAWINGS dicate like parts in the variousviews:

FIG. 1 is a fragmentary sectional view of aportion of our dry developersystem.

FIG. 2 is a side elevation of our dry developer system.

FIG. 3 is an elevational view of our dry developer system with partsbroken away and with other parts shown in section.

FIG. 4 is an end elevation of our dry developer system.

FIG. 5 is a top plan view of our dry developer system shown in FIG. 3with parts broken away and with other parts shown in section.

FIG. 6 is an end elevation of our dry developer system.

FIG. 7 is a fragmentary plan view of our dry developer system.

We have provided a dry developer system comprising a tray 426 supportedbetween developer assembly sideplates 428 and 430 carried by the mainsideplates 22 and 24 of the frame.

We dispose a developer roller 432 having a serrated surface 434 forrotary movement in the tray 426. A bushing 436 supported in theplate 428rotatably carries the shaft 104. We secure an end plate 440 of the tonerroller 432 to shaft 104 for rotation therewith so that when the shaft104 is driven in a manner described in ourcopending application supra,the toner roller 432 is driven. A stationary shaft 444 mounted in thesideplate 430 carries a bushing446 which rotatably supports the otherend plate 448 of the roller 432.

One end of a magnet support bracket 450 carries a lug 452 I which wesecure to the shaft 444 by any suitable means, such as by a screw 454. Abushing 456 on a portion of the shaft 104 extending inwardly beyond theplate 440 receives a boss 458 on the bracket 450. We dispose a pluralityof magnets 460 along the length of the bracket 450. The bracket 450carries a pair of spaced shield mounted brackets 462 to which we securea shield 464 by any suitable means, such as screws 466.

From the structure just described, it will be apparent that the magnetand shield assembly is stationary while the developer roller 432 willrotate in response to rotation of the shaft 104.

As will be described in detail hereinafter, in the dry developer form ofour machine, tray 426 normally holds a supply of a mixture of a magneticmaterial such, for example, as iron filings and a toner which may, forexample, be a suitably colored resin adapted to be attracted to thecharged areas on the copy material and thereafter fluxed to the copymaterial by the application of heat. In order to ensure that the mixtureof the carrier particles and the toner particles is as uniform as ispossible, we rotatably mount a pair of agitators 468 and 470 in thesideplates 428 and 430. These agitators are constantly driven to mix thetoner particles with the particles of carrier material. We mount a tonersupply housing 472 outboard of the sideplate 430 by any suitable meanssuch, for example, as by a screw 474 secured to an extension 476 of thetray 426 into which both of the agitators 468 and 470 extend. Housing472 carries a shaft 478 which supports an agitator 480 which, inresponse to rotation of shaft 478, stirs the toner particles within thecontainer 472. We provide the toner adder assembly with a gate 482normally urged closed by a spring 484 secured to'the sideplate 430. Whenin a manner to be described hereinafter, the supply of toner in the drydeveloper has become depleted, a signal is fed to a solenoid 486 toenergize the solenoid to draw its armature 488 to the right as viewed inFIG. 4 to permit toner to drop through the bottom of housing 472 intothe extension 476 from which it is moved by the agitators 468 and 470into the tray 426 adjacent the toner roller 432.

A pair of pivot shafts 490 and 492 pivotally support a clapper 494 onthe sideplates 428 and 430. We dispose a paper guide 496 below theclapper 494 ahead of the toner roller 432 in the direction of movementof the copy paper. The armature 498 of a solenoid 500 carries a screw502 which extends upwardly through a bracket 504. A spring 506 on thescrew bears between the bracket 504 and the head of the screw normallyto urge the armature 498 to its uppermost limit position as shown inFIG. 4. In this position of the screw, a lateral extension 508 on an arm510 carried by the clapper 494 rests on the head of the screw 502. Whena sheet of copy material is fed into the space between the guide 496 andclapper 494, solenoid 500 is energized to move the screw 502 downwardlyto permit clapper 494 to fall under the influence of gravity toward thepaper being fed to ensure contact between the paper and the materialcarried by the roller 432. An adjustable screw 512 on arm 510 is adaptedto engage a strike plate 514 to limit the downward movement of theclapper.

As has been explained hereinabove, the drive mechanism of our machinecomprises the chain 254 which drives a sprocket wheel 274 on shaft 104.Shaft 104 carries a toner roller drive gear 516 which drives an idlergear 518 carried by sidewall 428. Gear 518 drives a gear 520 carried bythe toner adder drive shaft-522 which is rotatably supported in theplates 428 and 430. Gear 520 engages respective gears 524 and 526 torotate the agitators 468 and 470.

The end of shaft 522 outboard of plate 430 carries a gear 528 which.meshes with the gear 530 carried by the shaft 478 of the toner supply.Thus, as the gear 516 rotates, agitator 480 is driven to stir the tonerparticles within the housing 472. It is to be noted that we provide awindow 532 in the underside of .thetray 426 to permit the dry developerto be monitored to We provide our assembly with an iron rod 534 disposedjust over the adder as it moves onto the toner roller. This rod is inthe fringe of the magnetic field produced by the toner magnets. ltcollects any stray particles to prevent them from falling onto the copymaterial as it moves through the developer system.

The overall operation of one type of machine with which our drydeveloper system is adapted to be used is set forth in detail in ourcopending application referred to hereinabove. As is pointed out thereinas a sheet of copy paper enters into the space between clapper 494 and aroll disposed thereunder solenoid winding 500 is energized after a shortdelay to permit the clapper to fall toward the paper being fed to ensurecontact between the paper and the developer material on the roll 432.Moreover, the developer concentration sensing system operates on lightfrom source 758 reflected by the developer to the photocell 762. 'As thepaper contacts the material in the serrations 434 of roll 432 toner isevenly brushed across the image to cause toner particles to adhere tothe charge bearing portions of the image. The rod 534 which is in thefringe of the magnetic field produced by the toner magnets 460 collectsin stray particles to prevent them from falling onto the copy materialas it moves through the developer system.

It will be seen that we have accomplished the objects of our invention.We have provided a dry developer system for an electrostatic copyingmachine which overcomes the defects of dry developer systems of theprior art. It produces clean copies. lt ensures that toner particles areevenly distributed across the face of the image bearing copy material.It avoids the necessity for using liquid developers.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations. This is contemplated by and is within the scope of ourclaims. lt is further obvious that various changes may be made indetails within the scope of our claims without departing from the spiritof our invention. It is, therefore, to be understood that our inventionis not to be limited to the specific details shown and described.

Having thus described our invention, what we claim is:

1. An electrostatic copier developing system for applying tonerparticles to copy material carrying a latent electrostatic imageincluding in combination a tray for holding a supply of a mixture ofcarrier particles of magnetic material and toner particles, A roller,means mounting said roller for rotary movement in said tray, meansdisposed adjacent said roller for producing a magnetic flux passingthrough said roller over a predetermined segment of its axis of rotationto cause said flux to adhere said mixture to said roller over saidsegment, a clapper, means mounting said clapper adjacent said roller forswinging movement from a position relatively remote from the surface ofsaid roller to a position relatively close to the surface of saidroller, means for feeding a length of copy material into the spacebetween said clapper and said roller and means responsive to saidfeeding means for moving said clapper from its remote position to itsclose position to bring said copy material into contact with saidmixture carried by said roller,

2. An electrostatic copier developing system for applying tonerparticles to copy material carrying a latent electrostatic imageincluding in combination a tray for holding a supply of a mixture ofcarrier particles of magnetic material and toner particles, a roller,means mounting said roller for rotary movement in said tray, magneticfield producing means disposed adjacent said roller for producing a fluxpassing through said roller over a predetermined segment of its axis ofrotation to cause said flux to adhere said mixture to said roller oversaid segment, means for bringing copy material carrying on image intocontact with said mixture on said roller and a collector of magneticmaterial mounted in the fringe of said field for collecting strayparticles of said mixture.

3. An electrostatic copier developing system for applying tonerparticles at a developing location to copy material carrying a latentelectrostatic image including in combination a tray for holding a supplyof a mixture of carrier particles of magnetic material and tonerarticles, a hollow roller, means mounting said roller ll'l sai tray adacent said location for rotary movement around an axis, mean comprisingan axially elongated magnet of generally regular configuration mountedwithin said roller in stationary relationship thereto with one polethereof adjacent to said location and with the other pole thereofadjacent to said axis for producing a magnetic flux passing through saidroller, a shield of magnetic material carried by said magnet mountingmeans and extending over a predetermined minor segment of the axis ofrotation of said roller, said segment trailing said one pole withreference to the direction of movement of said roller to cause said fluxto adhere said mixture to said roller over the remainder of the surfaceof said roller and means for bringing copy material carrying an imageinto contact with said mixture on said roller at said location.

4. An electrostatic copier developing system for applying tonerparticles to copy material carrying a latent electrostatic image,including in combination a tray for holding a supply of a mixture ofcarrier particles of magnetic material and toner particles, a roller,means mounting said roller for rotary movement in said tray, means forrotating said roller in a given direction around an axis, said rollerhaving axially extending serrations projecting from its surface, saidserrations being forwardly inclined in the direction of rotation of saidroller, means disposed adjacent said roller for producing a magneticflux passing through said roller over a predetermined segment of itsaxis of rotation to cause said flux to adhere said mixture to saidroller over said segment with at least some of said magnetic particlesextending in the direction of inclination of said serrations and meansfor bringing copy material into contact with said mixture on said rollerin a direction against the direction of movement of the roller surfaceto cause said toner to be brushed onto said material.

1. An electrostatic copier developing system for applying tonerparticles to copy material carrying a latent electrostatic imageincluding in combination a tray for holding a supply of a mixture ofcarrier particles of magnetic material and toner particleS, A roller,means mounting said roller for rotary movement in said tray, meansdisposed adjacent said roller for producing a magnetic flux passingthrough said roller over a predetermined segment of its axis of rotationto cause said flux to adhere said mixture to said roller over saidsegment, a clapper, means mounting said clapper adjacent said roller forswinging movement from a position relatively remote from the surface ofsaid roller to a position relatively close to the surface of saidroller, means for feeding a length of copy material into the spacebetween said clapper and said roller and means responsive to saidfeeding means for moving said clapper from its remote position to itsclose position to bring said copy material into contact with saidmixture carried by said roller,
 2. An electrostatic copier developingsystem for applying toner particles to copy material carrying a latentelectrostatic image including in combination a tray for holding a supplyof a mixture of carrier particles of magnetic material and tonerparticles, a roller, means mounting said roller for rotary movement insaid tray, magnetic field producing means disposed adjacent said rollerfor producing a flux passing through said roller over a predeterminedsegment of its axis of rotation to cause said flux to adhere saidmixture to said roller over said segment, means for bringing copymaterial carrying on image into contact with said mixture on said rollerand a collector of magnetic material mounted in the fringe of said fieldfor collecting stray particles of said mixture.
 3. An electrostaticcopier developing system for applying toner particles at a developinglocation to copy material carrying a latent electrostatic imageincluding in combination a tray for holding a supply of a mixture ofcarrier particles of magnetic material and toner particles, a hollowroller, means mounting said roller in said tray adjacent said locationfor rotary movement around an axis, mean comprising an axially elongatedmagnet of generally regular configuration mounted within said roller instationary relationship thereto with one pole thereof adjacent to saidlocation and with the other pole thereof adjacent to said axis forproducing a magnetic flux passing through said roller, a shield ofmagnetic material carried by said magnet mounting means and extendingover a predetermined minor segment of the axis of rotation of saidroller, said segment trailing said one pole with reference to thedirection of movement of said roller to cause said flux to adhere saidmixture to said roller over the remainder of the surface of said rollerand means for bringing copy material carrying an image into contact withsaid mixture on said roller at said location.
 4. An electrostatic copierdeveloping system for applying toner particles to copy material carryinga latent electrostatic image, including in combination a tray forholding a supply of a mixture of carrier particles of magnetic materialand toner particles, a roller, means mounting said roller for rotarymovement in said tray, means for rotating said roller in a givendirection around an axis, said roller having axially extendingserrations projecting from its surface, said serrations being forwardlyinclined in the direction of rotation of said roller, means disposedadjacent said roller for producing a magnetic flux passing through saidroller over a predetermined segment of its axis of rotation to causesaid flux to adhere said mixture to said roller over said segment withat least some of said magnetic particles extending in the direction ofinclination of said serrations and means for bringing copy material intocontact with said mixture on said roller in a direction against thedirection of movement of the roller surface to cause said toner to bebrushed onto said material.